|
Posterior Cranial Fossa
The posterior cranial fossa is part of the cranial cavity, located between the foramen magnum and tentorium cerebelli. It contains the brainstem and cerebellum. This is the most inferior of the fossae. It houses the cerebellum, medulla and pons. Anteriorly it extends to the apex of the petrous temporal. Posteriorly it is enclosed by the occipital bone. Laterally portions of the squamous temporal and mastoid part of the temporal bone form its walls. Features Foramen magnum The most conspicuous, large opening in the floor of the fossa. It transmits the medulla, the ascending portions of the spinal accessory nerve (XI), and the vertebral arteries. Internal acoustic meatus Lies in the anterior wall of the posterior cranial fossa. It transmits the facial (VII) and vestibulocochlear (VIII) cranial nerves into a canal in the petrous temporal bone. Jugular foramen Lies between the inferior edge of the petrous temporal bone and the adjacent occipital bone and transmits the internal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Of Skull
The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria. Structure Structures found at the base of the skull are for example: Bones There are five bones that make up the base of the skull: *Ethmoid bone *Sphenoid bone *Occipital bone *Frontal bone *Temporal bone Sinuses *Occipital sinus *Superior sagittal sinus *Superior petrosal sinus Foramina of the skull * Foramen cecum *Optic foramen *Foramen lacerum *Foramen rotundum *Foramen magnum * Foramen ovale *Jugular foramen *Internal auditory meatus *Mastoid foramen *Sphenoidal emissary foramen *Foramen spinosum Sutures *Frontoethmoidal suture *Sphenofrontal suture *Sphenopetrosal suture *Sphenoethmoidal suture * Petrosquamous suture *Sphenosquamosal suture Other *Sphenoidal lingula *Subarcuate fossa *Dorsum sellae *Jugular process *Petro-occipital fissure *Condylar canal *Jugular tubercle *Tuberc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cranial Nerves
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of vision, taste, smell, and hearing. The cranial nerves emerge from the central nervous system above the level of the first vertebra of the vertebral column. Each cranial nerve is paired and is present on both sides. There are conventionally twelve pairs of cranial nerves, which are described with Roman numerals I–XII. Some considered there to be thirteen pairs of cranial nerves, including cranial nerve zero. The numbering of the cranial nerves is based on the order in which they emerge from the brain and brainstem, from front to back. The terminal nerves (0), olfactory nerves (I) and optic nerves (II) emerge from the cerebrum, and the remaining ten pairs arise from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior Cranial Fossa
The anterior cranial fossa is a depression in the floor of the cranial base which houses the projecting frontal lobes of the brain. It is formed by the orbital part of frontal bone, orbital plates of the Frontal bone, frontal, the cribriform plate of the ethmoid, and the small wings and front part of the body of the Sphenoid bone, sphenoid; it is limited behind by the posterior borders of the small wings of the sphenoid and by the anterior margin of the chiasmatic groove. The lesser wings of the sphenoid separate the anterior and middle cranial fossa, middle fossae. Structure It is traversed by the frontoethmoidal, sphenoethmoidal, and sphenofrontal sutures. Its lateral portions roof in the orbital cavities and support the frontal lobes of the cerebrum; they are convex and marked by depressions for the brain convolutions, and grooves for branches of the meningeal vessels. The central portion corresponds with the roof of the nasal cavity, and is markedly depressed on either side o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arnold–Chiari Malformation
Chiari malformation (CM) is a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull). CMs can cause headaches, difficulty swallowing, vomiting, dizziness, neck pain, unsteady gait, poor hand coordination, numbness and tingling of the hands and feet, and speech problems. Less often, people may experience ringing or buzzing in the ears, weakness, slow heart rhythm, or fast heart rhythm, curvature of the spine (scoliosis) related to spinal cord impairment, abnormal breathing, such as central sleep apnea, characterized by periods of breathing cessation during sleep, and, in severe cases, paralysis. This can sometimes lead to non-communicating hydrocephalus as a result of obstruction of cerebrospinal fluid (CSF) outflow. The cerebrospinal fluid outflow is caused by phase difference in outflow and influx of blood in the vasculature of the brain. The malformation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells. Physiologically, brains exert centralized control over a body's other organs. They act on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows rapid and coordinated respon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endocranium
The endocranium in comparative anatomy is a part of the skull base in vertebrates and it represents the basal, inner part of the cranium. The term is also applied to the outer layer of the dura mater in human anatomy. Structure Structurally, the endocranium consists of a boxlike shape, open at the top. The posterior margin exhibit the '' foramen magnum'', an opening for the spinal cord. The floor of the endocranium has several paired openings for the cranial nerves, and the anterior margin holds a spongy construction, allowing for the external nasal nerves to pass through. Romer, A.S. & T.S. Parsons. 1977. ''The Vertebrate Body.'' 5th ed. Saunders, Philadelphia. (6th ed. 1985) All bones of the structure derive from the cranial neural crest during fetal development. Endocranial elements in humans In humans and other mammals, the endocranium forms during fetal development as a cartilaginous neurocranium, that ossifies from several centers. Several of these bones merge, and in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigmoid Sinus
The sigmoid sinuses (sigma- or s-shaped hollow curve), also known as the , are venous sinuses within the skull that receive blood from posterior dural venous sinus veins. Structure The sigmoid sinus is a dural venous sinus situated within the dura mater. The sigmoid sinus receives blood from the transverse sinuses, which track the posterior wall of the cranial cavity, travels inferiorly along the parietal bone, temporal bone and occipital bone, and converges with the inferior petrosal sinuses to form the internal jugular vein. Each sigmoid sinus begins beneath the temporal bone and follows a tortuous course to the jugular foramen, at which point the sinus becomes continuous with the internal jugular vein. Function The sigmoid sinus receives blood from the transverse sinuses, which receive blood from the posterior aspect of the skull. Along its course, the sigmoid sinus also receives blood from the cerebral veins, cerebellar veins, diploic veins, and emissary veins. See als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jugular Foramen
A jugular foramen is one of the two (left and right) large foramina (openings) in the base of the skull, located behind the carotid canal. It is formed by the temporal bone and the occipital bone. It allows many structures to pass, including the inferior petrosal sinus, three cranial nerves, the sigmoid sinus, and meningeal arteries. Structure The jugular foramen is formed in front by the petrous portion of the temporal bone, and behind by the occipital bone. It is generally slightly larger on the right side than on the left side. Contents The jugular foramen may be subdivided into three compartments, each with their own contents. * The ''anterior'' compartment transmits the inferior petrosal sinus. * The ''intermediate'' compartment transmits the glossopharyngeal nerve, the vagus nerve, and the accessory nerve. * The ''posterior'' compartment transmits the sigmoid sinus (becoming the internal jugular vein), and some meningeal branches from the occipital artery and ascending ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accessory Nerve
The accessory nerve, also known as the eleventh cranial nerve, cranial nerve XI, or simply CN XI, is a cranial nerve that supplies the sternocleidomastoid and trapezius muscles. It is classified as the eleventh of twelve pairs of cranial nerves because part of it was formerly believed to originate in the brain. The sternocleidomastoid muscle tilts and rotates the head, whereas the trapezius muscle, connecting to the scapula, acts to shrug the shoulder. Traditional descriptions of the accessory nerve divide it into a spinal part and a cranial part. The cranial component rapidly joins the vagus nerve, and there is ongoing debate about whether the cranial part should be considered part of the accessory nerve proper. Consequently, the term "accessory nerve" usually refers only to nerve supplying the sternocleidomastoid and trapezius muscles, also called the spinal accessory nerve. Strength testing of these muscles can be measured during a neurological examination to assess funct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vagus
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right vagus nerves—but they are typically referred to collectively as a single subsystem. The vagus is the longest nerve of the autonomic nervous system in the human body and comprises both sensory and motor fibers. The sensory fibers originate from neurons of the nodose ganglion, whereas the motor fibers come from neurons of the dorsal motor nucleus of the vagus and the nucleus ambiguus. The vagus was also historically called the pneumogastric nerve. Structure Upon leaving the medulla oblongata between the olive and the inferior cerebellar peduncle, the vagus nerve extends through the jugular foramen, then passes into the carotid sheath between the internal carotid artery and the internal jugular vein down to the neck, chest, and abdomen, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glossopharyngeal
The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper Medulla oblongata, medulla, just anterior (closer to the nose) to the vagus nerve. Being a mixed nerve (sensorimotor), it carries afferent sensory and efferent motor information. The motor division of the glossopharyngeal nerve is derived from the Basal plate (neural tube), basal plate of the embryonic medulla oblongata, whereas the sensory division originates from the cranial neural crest. Structure From the anterior portion of the medulla oblongata, the glossopharyngeal nerve passes laterally across or below the Flocculus (cerebellar), flocculus, and leaves the skull through the central part of the jugular foramen. From the superior and inferior ganglia in jugular foramen, it has its own sheath of dura mater. The inferior ganglion on the inferior surface of petrous part of temporal is related with a tri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Jugular Vein
The internal jugular vein is a paired jugular vein that collects blood from the brain and the superficial parts of the face and neck. This vein runs in the carotid sheath with the common carotid artery and vagus nerve. It begins in the posterior compartment of the jugular foramen, at the base of the skull. It is somewhat dilated at its origin, which is called the ''superior bulb''. This vein also has a common trunk into which drains the anterior branch of the retromandibular vein, the facial vein, and the lingual vein. It runs down the side of the neck in a vertical direction, being at one end lateral to the internal carotid artery, and then lateral to the common carotid artery, and at the root of the neck, it unites with the subclavian vein to form the brachiocephalic vein (innominate vein); a little above its termination is a second dilation, the ''inferior bulb''. Above, it lies upon the rectus capitis lateralis, behind the internal carotid artery and the nerves passing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
